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tv   Charlie Rose  WHUT  August 24, 2010 11:00pm-12:00am EDT

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>> charlie: welcome to our program. tonight and for the next nine consecutive nights everything a rebroadcast of our brain series with dr. eric kandel. >> we first of all have evolved to live in a second world and the brain of human beings has evolved to live in the world we live in. it's different in an snacks who have very visual spectrum wired than we have, they see a different world than we see. our capability of seeing the world is in part determined by this genetic program. we learn all the time how to recognize objects and we make those associations the next time we see an object like this. this involves alterations in the brain and this continues as long as we live. we continue to encounter new images, new people and we acquire that information and store it in the brain. >> charlie: 9 brain series -- n series with eric kandel coming up. understanding the brain, the series is made possible by grant from the simmons foundation.
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captioning sponsored by rose communications
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from our studios in new york city, this is charlie rose. >> charlie: this series is a journey to the most exciting frontier of science, the brain. every day we're learning more of how this miraculous organ works. last month was our introduction. we showed you the anatomy of the brain in the frontier where brain science was taking us. tonight we look at one of the most instructive areas visual perception. one quarter of our brain activity is about visual perception, so the brain is devoting about 25% of its power to vision. think bit. what the visual system tells us is that the core of our impressions of the world, what is real and what is beautiful. what is permanent and what is changing. vision is one of our five special senses including hearing, smell, touch and taste. we focused on vision because so much of our world is visual. also we understand more about vision than the other senses.
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most of us think that what we see is only determined by our eyes, but that is only the beginning. the extraordinary happens in the brain as it takes the inverted image from the retina and passes it to the cortex where the brain creates a perception of the seeing world. it is in the brain where seeing happens. patterns of light and color are translated into objects and events. things that are meaningful for us and our survival. so the question is, how does the brain produce our perception of what the eye has captured. that's the difficult and the exciting part. how does this computation work. how does the brain organize the patterns of neural information into the visual perception we v how does it make inferences about the world around us. what clues does it use and how does it compensate for changes in our visual environment. what assumptions does it make. how much of its activity is
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passive and inferential and how much of it is the active collection of information? we know from the study of the development of that visual experience in the very first years of life when neurons and their connections are being forged is crucial for normal vision. we're also learning what happens if during these early years one is deprived of visual experience. there is now encouraging news that the visual system is surprisingly plastic and able to recover from injury and to learn anew. we will ask what we know about blindness in various forms and we will learn more of the relationship between vision and other sensory processes. this evening, we're joined by a remarkable group of scientists who are devoting their life to understanding how the brain creates visual perceptions. they are tony movshon. he is interested in the way the
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brain encodes and desoadz visual information and the mechanisms that use the information to ensure the control of behavior. he analyzes neurons in the visual areas of monkeys and is on the faculty at new york university. he has a dact trut in neurophysiology and psycho physics from cambridge. ted agentsson is professor of vision sign in the department of brain and cognitive sciences at mit where he focuses on topics in human and machine vision motion analysis. he is an expert in many things drug the gestalt theory of perception. he has a ph.d. in experimental psychology from the murts of michigan. nancy kanwisher is the professor of the institute at m.i.t. they have identified developer regions of the brain that plays roles in visual perceptionist specially in face recollect model. pawan sinha is so is yacht professor in neuroscience at m.i. tinchts where he leads the lab. he has done amazing work in india as a part of a project for
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children who suffered injury or disease to the eye. in answering these questions, once again my cohost, my guide, my professor is dr. eric kandel. he is as you know from our program a noted brain sign test. he's a noble laureate. he's affiliated with columbia, the howard hughes ion substitute has written a remarkable book about the search for memory and he is for this program a great friend. so i am pleased to have his wisdom and his direction guiding us as we try to learn more in this multipart series about the brain. welcome again. >> thank you charlie, always a pleasure to be here. >> charlie: we look at the introduction in our first episode. tonight you've chosen visual perception. why do we start there. >> we chose this together, charlie. we chose it because we understand the visual system better than any other system of the brain and because it is a model for how the brain works. if we understand how vision works in the brain, we have a
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very good understanding of how the other sensory systems work. >> charlie: you have suggested sort of four ways that we ought to look at this. the eye is not a camera. sensory functions are localized. visual computations are hierarchical and plasticity in the brain is pervasive and crucial. take me quickly and summarize what we mean by the eye is not a camera. >> you've made some of these points. the eye takes incomplete information from the external world. it is not absolutely faithful to the external reality. it takes things that are important, it throws other things away, it emphasis certain parts of the image and discards others. the brain is the creative organ that makes sense out of this. it gives you a feeling of three dimensional face of spaces looking at you. that's a complete reconstruction done by the brain. the brain does this in an orderly fashion.
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each sensory system, the visual system is a perfect example. has a specific spot in the brain, so there are a series of relays that localize everybody's brain in exactly the same way. and the visual system has its own space, the touch system has its own space, the smell system has its own space. every sensory system has a specific location. and it is organized in the hierarchical fashion. there are a series of relies that operate on the information in progressively more complex fashions. we'll see the early relays, the retina and the thalamus, see whether or not light is present or absent. they respond to small spots of light. as we get out to the cortex, the cells in the cortex begin to respond to edges, to bars where they are horizontal or vertical. later on we get to more complex images and ultimately we'll hear from nancy kanwisher how the
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brain respond to faces of the land escapes. this is a progressive processing operation that the visual system performs. >> charlie: tell me about illusions. >> the brain makes guesses. as a result it could be deceived and we can sometimes present it with a two dimensional form that it sees as a three dimensional form and vice versa. one can actually see the creativity of the brain at work. because in solving an illusion, figuring out that there is a dog here or there's a face here, there's almost a high experience. like a sense of creativity. in the very primitive sense, we see in the visual system of everyone, you, me and the person in the street, the creative process that is probably specialized in genuinely creative people that do great science or art. the elementary forms of this creative process is built into the brain. >> charlie: we begin this conversation talking about how
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exciting this was. you'll see that now as we go to the conversation that eric and i had with a very very distinguished panel. here it is. let's begin by looking at the anatomy, our anatomical expert is with us again. welcome back. >> my job is to tell you where things are. we have pictures and having started with the idea that the eye is not a camera and that's not how the visual system works. we'll show you the eye does form engines like the camera does. this is a cross-section of the eye taken as if through this plane. in other words if someone had taken my eye and divided it in laughfront of my face. an image is being formed in the point of the world. the light rays are focused like a camera or light system focusing on the ray on to the retina which lines the whole back of the eyeball. the optical apparatus at the front of the eye works like
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other optics we understand. there's a corner know which provides most of the power for forming the image and the lens which is the adjustable part of this system that lets us focus on near and far objects. now, what we're mostly concerned about here though is what happens once the information reaches the rt know and norms an image on the retina. @ thaint the photo receptive cells that line the back of the eye collect the information from the image and funnel it through this single rather narrow channel the optic nerve. now the eye is doing something very dramatic right away in terms of neural function and neural circuitry. the retina is part of the brain. the fact that it happens to live in the eye is a matter of anatomical convenience. but the retina contains the kind of circuits we find in the central nervous system and those circuits perform elaborate computations most of which we're not talking about in detail today. one of the striking thing the retina does is something we're familiar with in terms of for example how a digital camera works or a video many cholera
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works. we take a lot of information and we can press it down so it will fit conveniently on to our tapes or our hard drives. the retina has about a hundred million photo receptor cells which senses the color and light at each point of the image. the information from those receptors is compressed down so it comes out of the eye along the optic nerve in a million fibers. there's 100 to 1 compression made by the circuit of the iso what transfers into the brain can be organnably for physical reasons carried along the optic nerve. one of the things about the eye that's very striking aspect of its design is that its visual resolution, its acuity is only very queue at the center of gaze exactly where you're looking. if you look carefully at eric kandel's face for example as i am, and then try to work out the detail of what color shirt that sinha on my left is doing. you can't do it because the visual acuity falls off.
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that's because your retina is very specialized for detail in the middle and its sensitivity falls off to the periphery. as a result you have to move your eye around. so the way you make up your picture of the world is by moving your eye from place to place and capturing multiple snap shots and assembling them into a person. it has to be said all of us here work on the signal nervous system and most of what we talk about today has to do with what the signal nervous system does. we're looking at a view of the brain from the back. this same brain we have in the middle of the table. a colorful representation is here rendered and what you can see here is a cone of light rays forming an emergency entering the eye which is -- image entering the eye. the optic nerve passes here as you can see into a relay nucleus in the core of the forebrain called the thalamus. the this nucleus here is a relay
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nucleus. the thalamus is a core of the brain which connects to all parts of the cerebrum cortex that sheet of cells we discussed before that does most of the commutation that the brain does. signals from the visual thalamus pass to the visual areas of the cerebral cortex which are marked here some of them in different colored. >> you show us the outline, this is characteristic of the sensory systems. there's a hierarchy, there's a series of relays that process information and progressively more compact fashion. that's why this is such an instructive system to study. >> charlie: ed what is the most awe fizzing part of this for you. >> the most amazing thing is the fact that the visual system is so successful in putting this information together. we know from our research in machine vision where we try to make robots replicate the functions of human vision, we know this is much more difficult than it seems because it's turned out to be extremely difficult to get the computers and the robots to do anything
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like what human vision does. so the problem is, in order to put the information together, you get all kinds of little bits of information, which puts together into a coherent whole. all of the bits, each of those bits, each of the little edges or lines or whatever you get is committeely uninterpreted by itself. so you have to figure out how to bring it altogether and that turns out to be very difficult thing to do 123450eu6789 wha. >> charlie: what do we know about how the brain make these inferences about the signal that it's getting? >> well, we know that there is this hierarchy, these multiple levels, each level of analysis putting together information that it's getting from the previous level and combining that with information that we have stored, information based on our experience in the past with other kinds of similar images and objects.
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we don't know in detail how that happens but we know that's the critical thing. >> we also have some very good physiological experiments that indicate how the processing steps occur. and we have very good insight what happens with the earliest stages even at the latest stages and they give you clues as to how the more complete image is mooput together. >> let me show you some examples. i'm going to show you some 50-year old home movies. to revolutionize the field and won the nobel prize for the work. and what they did is based on a system that's shown on this diagram. the brain is the same brain that we become familiar with. the eye i hope is now also the same eye that we're familiar with. and this simply shows the experimental set up that was used to make recordings from
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brain cells in animals while they were actually viewing targets on a screen. so you're going to see three video clips. and in each case what you're going to be doing is looking at the screen shown over here as if from the animal's eye point of view the you're going to see the images projected on the screen. you have to bear in mind that is home movie quality. it does not look like it was made in the studio. these images will move around. the information from the retina passes into the brain along the matt waypathways and crosses the activities of the nerve cells this change. nerve cells communicate with one another as we discussed in the first program of the series by firing these trains of impulses. this is the nature of the signal that cells use to communicate over long distances. >> morris code. >> it is a digital code. because of the constraints of building a brain, the brain can't use the kind of code that a computer would use. it has to use a code which involves the transmission of
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information along these long axons which form the nerves for example the optic nerve. the transmission of that information is by these empulses which is what we hear when we make these recordings. the picture will be the image on the screen and the sound will be the recording coming from the brain cell. now in the first image, in the first film what we're going to see is a set of stimuli that are causing changes in the activity of a cell recorded from primary visual cortex and the first segment of the film is simply going to show the map of what we call the receptive field which is simply the region of the retina within which visual stimuli can influence the firing of the cell. first you hear hearing the brain's activity.
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the point of the next segment of the film is to show not only is the firing of the cell is specific to where on the retina the image falls but this particular cell will only be activated when the target has the right orientation. the cell will respond to a line, a line moving in one direction and of a particular contour orientation. very little activity all through here. beautiful. very powerful stroking activity. one nerve cell. >> this is reelg the conversation that neuron is carrying out. >> if you reflect back for a moment to the question of whether the eye is a camera, a digital camera captures the light and color of one pixel of an image. clearly this cell is doing something completely different from that because it is telling you not about the light or the color of the pixel but it's
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telling you if a line of a particular orientation moving in a particular trekio direction is present in that place in the visual field much it's giving you a very specific piece of information about the component of the image. now you might ask where the cell gets that information from. as it turns out we know from a number of experiments that the transformation of the information takes place between the thalamus, this relay in the middle of the brain and the cerebral cortex. if we show images of the kind i've just shown you to the neurons recorded in the thalamus. that neuron will have very little specificity. in fact if you look at this video what you'll be seeing basically is a cell that's firing. again you'll hear it and the audio track is really vigorous whenever there's light in the middle of the screen. this cell just cares about light. >> i just want to elaborate on what tony said because it's so important.
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this transformation that you see from the cells to the cortex primary visual cortex but it's a spec tack include because it made one realize that the cortex does a lot more. the lateral -- showed response. in the cortex in response to barbsbars, to edges and differet cells will respond to edges of different orientation. vertical, horizontal or oblique. so there's a tremendous specificity in the whole transformation of having circular fields to linear is a major operation that the brain performs. you can imagine at later stages you can put lines together to have corners, ultimately to have faces. so this is the beginning of how the brain reconstructs a visual image. >> charlie: tell me about how you have begun to understand and focus on the localization of
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function. >> well, our work builds on not the prior work using behavioral measures. so we're interested in face perception. one of the reasons we chose to work with face perception there were lots of reasons to think that the brain would have special machinery for processing faces. so if we show that movie, you'll see in the display that when a face presented upside down you can't tell what it is. this is characteristic of faces in particular. you don't see it for other kinds of stimuli. it's perfectly easy to recognize a chair or a dog or a tree if you see it upside down whereas face recognition is severely impaired. pause of that work and other work like it, there was reason to think that the brain has special mechanisms it uses when it recognizes faces. the idea was that at the higher level stages from where tony has been talking about, the higher
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stakes of the visual system there might be special machinery in there for face recognition. we've looked at that, the brain origin methods where you hip a subject in a scanner and show them faces and you can see that part of the brain turn on in brain imaging methods when a subject looks at faces. so right now, my face area which is right there in my brain is active because he'll looking at your face. and that was off now it's on, now it's off. and i know that because i've scanned myself and hundreds of other people looking at faces and you can just see it turn on and off. >> charlie: th fact that face recollect nation has localized function is more or what. >> i would like to know which mental functions gets their own recognition from the brain and which don't. in my lab we found a few. we found regions for face recognition right here on the brain i can show you where it is. that's the brain looking at you. if we turn it upside down so you
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can see the bottom of the tim prul lobe righ -- temporal lobet face area is right here by the brain. we also found other specialized rages. so we find that face region because of the work that eric just mentioned on people with brain damage. when they had damage in this general reablg they tended to -- reg theregion. it's really fun to discover. but since then we found several other regions that we didn't expect in advance at all. one of the regions that responds when you look at places and land escapes and it's right next door, a little further forward right about there in the brain on both sides. >> charlie: let me just ask this question. if in fact i can reach inside of somebody's brain and remove the part of the brain which recognizes lan landscapes. and then that person would look at a landscape. what would they see. >> well we've tested stuff a
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person. years ago when we first discovered this place area here, i was dying to know what life would be like for somebody who didn't have that region. but it's actually on both sides of the brain so the chance of getting brain damage on both sides is very unlikely. i was at a conference once and i was walking through these rose o --rows of posters and i saw somebody with a braij damage right there on -- brain damage and i said who is that person i need to test them. so i tested this guy who had been an artist, painted these beautiful paintings, very tragic and he no longer painted or took joy in looking at things. interestingly he could see where hgoing. he could recognize faces, he can read and get around in the world but as he told us, he never knows where he is. >> he can see it but -- >> he doesn't know where it is. >> this is also true for the face area. >> charlie: what happens in the face if that's removed.
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>> if he moves the face area selectively just that region, the typical findings that people can recognize, all kinds of other things. they can iraqi nay recognize las and sobs but noobjects but not . even more astonishingly there's one or two patients who have the opposite situation. they have more diffuse damage and they can't recognize objects but one guy in particular is very impaired, can't read, can't read objects, he's functionally blind except he's 100% normal on the face recognition. that tells you even more strongly than the loss of face recognition that you can have selective preservation. it's not a special fancy system that builds on top of the object recognition system it's a separate processing. >> i think this shows two things. it's principals that govern how
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the brain functions. one is that there's a hierarchy. you don't see this at the early stages of the visual system. they don't respond to faces. this is a very complicated deceptual function, sort of in-stage of the visual system number one. and number two, this tremendous localization of function so the brain is largely organized because different kinds of representeddations touch, pain, vision, hearing, smell, taste, localize different regions of the brain. this is a two-key organizing principles, localization, function and hierarchy. now how do you set this up? one of the clues whereby the brain is able to put objects together. this is things that they've been studying and they can tell us how they get to a point where you recognize faces.
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>> it's a big question and we still are at the starting box in our understanding of how this process unfolds. but in many so of the work that we're doing, we are trying to approach the cushion by awe daunting a somewhat unique approach of working with children who have been blind for several years but they have treatable blindness. if you have, say, a ten year old who has never seen form until that point, and you're able to surgically initiate vision in such a child, then you have a remarkable opportunity of then following the progress of this child and studying what kinds of mistakes do they start out making. >> charlie: what do you discover. >> what we discover is the initial stages after the operation in time are fairly disordered. in the world to such a child. in fact, let me show you some images. so here's a child who had a
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catarat, a dense ca catarat whih like if you were to be wearing pingpong balls cut in half, that's the level of vision such a child could have. after such a child gets vision by re moving the catarat and implaptdinimplanting a clear ler world is very unlike or the person is very unlike our perception. if you show to such a child an object to us that's instantly recognizable and you ask him do you recognize this object, they do not. then if you ask them well if you can't name the object just point to where the objects are, they point to every little region of the different color o or e loom nuns. it's different colors -- >> charlie: and intensity. >> yes, yes. so the world is greatly broken up into many different regions.
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in fact, as i think edges are a key construct in our visual world and b are very easily we as mature visual observers, we are easily able to tell that this edge is due to shadow, this edge is due to depth of continuity but to a child who is just starting to see edges on edges seems to have equal experience. so for search a child, even the shadow on this ball becomes an important edge. and the world gets fragmented into all these pieces and they're unable to glue it together and see coherent objects. >> the act of going from light in color the retina to objects and events in the world is a matter of assigning these edges properly. this is something ted has done a hot of work on and has some -- a
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lot of work on and has some examples to show. >> this is a good one. this is a famous old example of the principles of gues yes, sir. when you look at this picture it's hard to figure out what it is. it looks like a bunch of light and dark splotches and you may look at it for a while and see light and dark splotches. that's the information your eye is getting from this picture and your brain has to figure out what to do with it. now i can show you what you should do with it because we appeahave drawn some lines on to show you there is a dog there, the dalmation dog and the dalmation dog has these light and dark spots on it. if we go back to the original picture, isn't it unbriefable.
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>unbrief. >> fantastic. >> normally in our normal vision everything seems so automatic we don't realize this is really what's going on all the time. our eye gives us this light and dark information but it doesn't come in an organized form. and the problem is light and dark can come from many different sources. it can be a light or dark spot because the if you are has black or white pigment in it or it could be some shadow that's being cast causing it to be light or dark or it could be the edge of the dog where the dog stops and the background starts. so this information that you're given at the level of the eye is very ambiguous and so there's a sort of a detective problem, a problem-solving task that the brain has to deal with which is how you piece all these bits of information. each piece being ambiguous. how do you piece it altogether into a single coherent or
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especially bustory or. >> charlie: in the midday sun, the afternoon and then at dusk. the tree would remain the same in our vision even though the shadows and the light and intensity would change. what about that. >> that's one of the amazing things that vision has to do. because the brain is designed to pull out the information that's stable and important and meaningful and to throw away the information that's sort of accidental. we have another illustration of, this is a picture of a cylinder casting a shadow on a checkerboard and you'll see there are two checks, there's a dark check labelled a and a light check labelled b and it's
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quite obvious when you look at it that one of them is dark and one of them is light. the fact is the ink on the page is exactly the same. if you were to be a light meter and you measured the gray level of the ink for a and b it's exactly the same ink. so it seems like a failure like the visual system is not managing to do this simple thing to tell you what color the ink is on the page. the visual system's job is not to tell you about ink on the page it's about to tell you what's out there in the world. >> although this process can be written down and described the way ted describes it, you would have thought you could unpack it. you could have said now that i know a and b actually have the same color on the page, i should be able to see them as though they are the same. but you can't. it's absolutely automatic. it's built into a low level of the original system to tell you about the checkerboard and not about the shadow. >> charlie: when does most of this development in our brain about visual perzippion take --
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perception take place. >> initially i started out with the worry that a child who has been blind for the first several years would probably have lost the ability to acquire vision. >> charlie: blambrain. >> charlie: brain would then -- >> shut down. maybe the three or four years are the critical periods for learning vision. if that was true then what we're doing in this project would not be serving a purpose either for the child or for science. i'm happy to report that even children as old as 14 or 15, the oldest is 29, ebb with individuals as old -- even with individuals as old as that when you restore sight, you see significant improvement in vision. the acquisition of visual function, which goes to tug that
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the programs for learning, the programs for acquiring vision can be initiated evenly in life. yo>> you can see this in differt brain areas so each of us learns to read. when we learn to read there's a particular part of the same visual area of the brain that i was talking about before that comes to respond selectively to words and letters presented visually. and it's right in there. it's very small but you can finds it in almost every subject. since people have only been reading for a few thousand years, humanity hasn't been reading very long, that piece of brain cannot be the product of natural selection. so it must be that each of us in our life span wires up the circuits based on experience to make that region selectively responsive to the languages that we know. a colleague of mine has recently shown that that region can develop even if you don't learn to read until well into adulthood. so he found, first of owl he
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found that region -- of all he fond that region in chinese characters but then he found a bunch of chinese ill lit ruts and scanned them and then he taught them to read and then he scanned them again. and there it was. some of these people were 40 when they learned to read and that region still developed. so some of these reasons are extremely plastic and can develop late in life. >> charlie: they come alive so to speak. >> that's right. >> the plasticity that people like nancy and others have shown in the brains is very impressive and it i& theand the critical po exist. there are some aspects of visual development and other kinds of development that do end at an age of three four or five. it's a vision that's very clear. if you grow up with your eyes
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misaligned so they don't point in the same direction or you have a subsequent, th squint, tr vision, department in space by comparing the images in the two eyes break down and they lose the ability to have that function. once you've lost the ability to do binocular vision is not remade by the able of three or four then it's gone for life. there are some functions for which plasticity is not a remedy. so one of the interesting things, the challenge that pawan's work has presented us we thought for a while everything was pretty much done and dusted by the able of five. now we realize there's a whole variety of things some of which remain plastic for quite lodges periods in life. >> there are two lessons important for this. even in pawan's work when is vision of acuity. obviously the earlier one's thought of corrective procedure the better off one is.
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the fact that pub can rescue an --man ca --man can -- pawan , these cataracts are quite common in certain populations in india, this has been a major public health effort that as he pointed out is not just for the kids but imagine having a child who is blind. you feel that their life is really tossed away and you can restore vision and recognize faces. it's a fantastic medical achievement. >> charlie: this is a little bit off again but if you take a kid and, from the moment of birth and then later. >> there's extensive literature and visual deprivation. if you take an experimental animal and you raise it with no light or vision, it seems to be perimently and row foundly disrupted. >> charlie: permanently. >> permanently and profoundly.
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there's some recovery but it's much less striking than the discovery pawan sees in these kids. >> charlie: the difference is what. >> in dark rearing a kitten you're depriving the visual system of all input. there's no light reaching, there's no stimulation reaching it. the children we're working with who have cataracts, throughs some light and maybe there's there's some rudimentary amount of motion. if you put your hand in front of the peas they can tell -- eyes they can tell something is lightening or dark thing. >> you want to show how kids are covering the visual capability and how similar it is to the dog. >> absolutely. if we were to roll the video ... so this starts out by outreach, identifying children who need treatment. during this video, you see us
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working in the school for the blind and we are screening the children to see which children might have a treatable condition. most of the children we encountered there have permanent conditions. there were several children we found who had light sensitivity, which is initial encouraging signs, the condition might be treatable. so what you see in the video is the child responding to light, even saying where the light's coming from. we then bring the children for the exam and the children who we find are in fact treatable, we do an ultrasound of their eyes to make sure that the posterior segment of the eye is all fine. both children are then provided treatment. and we then monitor their progress. so in the video you see a child
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who has congenital cataracts in both eyes. so until this point the child has very few prospects for later in life. but this child was then given surgery, clear acrylic lenses were implanted into his eyes and what you see in the video is him three weeks post operatively and he is now responding to visual cues. >> a lot of what we've learned have come from what we've discovered to injuries the preenthebrain. >> absolutely. we're a long way from being able to fix that vision right there from brain damage. >> one of the reasons you can tell that is both of you have had experience with -- and you might just sort of discuss how difficult it is to even come
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close to the way the normal visual system. we can recognize each other's faces with enormous facility, computer vision has enormous difficulty doing that. >> it certainly is true and a lot of very smart people have spent a lot of years with very powerful computers. we get better at it year after year but it still is true that the ability of computers to do any kind of simple recognition is still very primitive. and as the computers get more powerful, they just in terms of their processing speed and their memory getting more powerful, they get better. but it's clear that we're still missing some fundmental insights about how this needs to happen because all i can say is the computer vision systems even as they're getting more advance, they still fall very far short
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from what human vision can do. >> charlie: what computation can do. >> i can give you one specific example of that. face recognition, the cutting edge computer visual system would require a facial image that was at least 100 by 150 pixels in its resolution. the human visual system can work with images as great as this. these are maybe about 12 by 14 pixels images. and we can achieve recognition rates on these images that are superior to a computer vision system working with images that have a hundred times more resolution. so just that said, it's not, it doesn't seem like we can get to this level of performance just by making incremental improvements. we need to have a qualitatively difference. >> one of the things that's key to the visual system's success
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in doing this is what ted was talking about earlier which is the ability to throw away the information that's incidental. so to throw away where the light happens to come from, how the fast happens to be posed, where the shadow -- >> charlie: do we know how that happens. >> we know from the cylinder on the checkerboard what some of the principles are. we do not know how exactly that happens in detail. if we did, we would have written a computer program to do it and the computer would be as good as we were. >> this is no just a cube. if you have a wire-framed cube you don't have any difficulty interpreting it as a cube. if you have a wire-framed cube of which you've made an image on a piece of paper. as for example on the case of the images here, there is a stability to the image. you can see this image in two different ways. so if you look at the cube on this side, what most of you will do is see this as a cube with this face near and this face the one that's behind. the cube on this side which has
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information encoded in a slightly different way in the image will represent itself with this face near and the other one far. now if you look at the cube in the middle by simple inspection or by an effort of will, you can actually see that cube in either form. you can't see it both ways, you have to see it one way or the other. one of the striking things about this cube in addition to its flipping is the one thing you don't see is actually in many ways the simplest thing you could see. so here's the new yorke new nece as i hold it up, it's in fact a flat object which isn't a cube at all. it's in many ways the simplest possible interpretation of the image. it's just a series of lines on the paper. this interpretation is the one you never see. my question is why the visual system constructs this three dimensional representation out
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of the information is one of the questions we'll have to answer if we're going to answer questions about for example how complex objects are represented and recognized. >> charlie: one broad question, eric, the notion between genetics and environment as it influences everything we talk about here. >> well the genes terms 9 the basic line document of the visual system. if you interfere with the genes involved in the development of the visual system, you will not have normal functioning vision. but given that so that the basic neural circuit is worked out by genetic and developmental processes. plasty can occur at every one of those relays particularly at higher cortical areas who modify how we use it. we first of all have evolved to live in a certain wonderful and the brain of human beaks is evolved to live in the world we live in. it's different from snakes who have very visual spectrum that
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is wider than we have. our capability of seeing the world is in part determined by this genetic program. but we learn all the time, we learn how to recognize objects and we make those associations the next time we see an object like that. so this involves as a resultations in the brain and that continues as we life. we continue to encounter new images and new people and we acquire that information and store it in the brain. so both are involved. >> a lot of new information just in the last few years about the relative roles of genes expiks perience -- experience and setting up the whole picture and it's getting very tantalizing. the fact that babies who are one to three days old have pretty good ability to distinguish one face from another even if there's no hair or external features, just the internal part of the face they can discriminate. and they can do it for upright faces, not inverted faces like
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adults. so if possible, that's learned in the first one to three days. but it sales more likely that part of that fashion system may be word wider in and waiting for experience to embellish it. >> charlie: let me go around the table and say what's the most important thing you want to know. >> my specialty lies somewhere in between where they left off. they did the work in the early 60's. and what they did was basically described the early processing of visual information that brings information to the visual cortex. now what nancy's described is a lot of work that has to do with the highists levels of pathway processes information about faces and places. my own interest and the challenge that i and my colleagues would like to solve has to do with how the information from this single representation and primary visual court text gets channeled through this whole set of areas
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which are at least 30 or maybe more until it reaches this high level of representation where things like faces and places get processed. there's a great deal of what we often call mid level vision which as a representation in the cortex in many different places and areas so the challenge i think that we face is basically to braij what the brain is what. >> charlie: ted what would you motion like to know. >> i want to know the computations in order to tell the difference between light and shadow, between light paint and dark paint. just very simple things, things that same simple to us but which apparently involve very sophisticated computations. >> charlie: is that about -- >> some day we'll figure out why it is but it's the ways you take all these numbers that the eye is giving you, light and dark in color. take those numbers and recombine
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them into something sensible that tells you about the world. that's t the problem, theoreticl problem of human vision and the practical problem with computer vision. >> i want to understand just how the mature visual system works but how it gets better. how is the progression of learning, starting with the feed. what are the principles of learning that's different. what's the scaffolding that sports the later flowering -- supports the later flowering of all the visual skills that we have. >> i want to know why we have these special regions for faces and places and bodies and some others i didn't mention. the one for thinking about what other people are thinking. possibly regions up here, over here especially involved in language. why do we have special regions for those functions and apparently not other ones. and how do those functions land
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so systematically in the same place in every normal subject. >> charlie: eric. >> i'm interested in sort of two enter related questions. one is what autistic children don't look at other people directly in the eye. they have a difficult time processing the social interaction. what is going on and to what degree this is in effect the aspects of visual perception or what degree reflects other aspects of social directions and how these connections are very interesting. also visual perception of course is so important for the enjoyment of arts and i would think that as we understand more and more why it is that exaggerated images of people haddive a powerful effect on us we have a better understanding how we respond to certain works and arts. i understand dialogues between people sitting around this table and not only art historians but artists each informing each
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other how the brain works. the artists are doing experiments with visual perception all the time and they're finding out better and better ways in order to get a positive or negative effect on people looking at their work so far. >> charlie: so there was this panel that i enjoyed enormously and learned a lot. but what should we take away? what do you want the people at home who see this to come away with? >> i think the important thing to learn is how sympathetic the brain is. how it lives in a world from which it extracts limited information and how much of what we know about the world is reinstructed in our brain. this not only holds true the vision, it holds true for all senses. we see the complete picture even though we get fragment tree -- information. we also realize house remarkably plastic our brain is. we're constantly made figure our
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view of the world as we learn more bit. and in case of injury we disrupt function of vision but in many circumstances there's the capability for recovery as we saw in these kids. >> charlie: next month you'll do what. >> next month is a natural extension of sensory systems. we're going to discussion action, movement. the reason sentation is important and build up a rendation of the outside world is i wanted to interact with you, i want to be able to shake your hand. how do i read out and see where your hand is located. this is really the magnificent computational tasks that the brain accomplishes this time in terms of movement. and that's what we're going to ache up next time with another outstanding group of specialists. >> charlie: i look forward to it. thank you for joining, see you next time.
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